1. Field of the Invention
The present invention relates to an apparatus for producing bulked yarn by way of treating multifilament yarn with fluid.
2. Description of the Prior Art
Techniques for imparting compactness to a multifilament yarn in which the yarn is subjected to action of turbulent fluid are well-known in prior art. Examples are U.S. Pat. Nos. 2,036,838, 4,063,338, 3,823,449, and 4,251,904. The purpose of such a yarn treating apparatus is to obtain a synthetic multifilament yarn which offers bulkiness, compactness and convenience in further processing. These qualities are best achieved if open thick yarn portions and compact entangled portions appear alternately. The larger the number of entangled portions per unit length is, the stronger the final yarn product becomes.
An air or fluid jet apparatus is preferrably employed to obtain these qualities since alternative methods such as twisting or sizing procedures have several disadvantages. If the yarn is sized, it is necessary to wash the textiles fabricated therefrom in order to remove paste. If the yarn is twisted, a twisting machine will be required. In any event, the number of treating processes will be increased, the production cost will be increased, a rewinding process will be required, and the probability that the yarns will be injured is higher. The fluid jetting apparatus avoids these procedures and obtains the entanglements by fluid turbulence in the yarn path of the apparatus. Such fluid jetting methods enable one to obtain a product of the same quality as twisted yarns with the separation of filaments being controlled in spite of being untwisted.
However, the treating of yarn with fluid has created several problems in connection with certain conventional apparatuses. While the processability of the yarn may be enhanced by imparting compactness and cohesiveness to the yarn by interlacing individual filaments in the yarn, the bulkiness of the yarn decreases and the appearance of a fabric made with such yarn deteriorates as the processability is enhanced. The relationship between bulkiness and processability is more advantageous if the entangled and not entangled portions appear regular and if the number of entangled portions per unit length is high. Although conventional apparatus try to obtain a more satisfying relationship between bulkiness, processability and cost, they have been less successful than the present invention. One reason for such limited success of prior art apparatus might be that in almost all of such conventional apparatus, the yarn path enclosure is cylindrical in form. The cylindrical enclosure is provided with an air jetting port for jetting air onto the yarn, e.g. U.S. Pat. Nos. 4,188,692, 4,070,815, 4,064,686, 4,063,338 and 4,138,840. The specific construction of such conventional apparatus differs. For example, the length or diameter of the cylindrical enclosure may be changed, or a slit may be formed along a longitudinal direction of the cylindrical enclosure in order to make the passage of yarn easy. Nevertheless, they offer the problem that the consumption of air or fluid and the necessary pressure is too high compared with the achieved number of entangled portions and the strength of these portions. In addition, the entanglement is not solid enough, and tension and relaxation with only small force extinguishes the entangled structure of the yarn and the gathering property is frequently lost.
It is an object of the present invention to solve the above described defects and to obtain with a smaller quantity of fluid a yarn which has a high number of entangled portions of good quality and processability. The special, although simple, construction of the invented apparatus enables one to achieve these advantages. Instead of being cylindrical, the enclosure is formed by a yarn path part in the present apparatus, which part is defined by planes arranged in the yarn traveling direction. In the preferred form, the enclosure has a triangular cross-section. This form of yarn path enclosure insures a uniformly interlaced yarn because it avoids the unidirectional and continuous rotation during the interlacing procedures. One prior art device that employs a similar construction of the yarn path enclosure is U.S. Pat. No. 4,251,904. However, in contrast to the present invention, the yarn path part of the present invention is interrupted by an intersection which constitutes the yarn treating section and is defined by curved faces and planes having a cross-section larger than that of the polygonal part (e.g., triangular cross-section) of the yarn path part. The specific construction of that portion of the yarn path effectivates the desired mode of entanglement as described below.
All other known prior art differ even more than the aforementioned patent from the present invention. For example, in U.S. Pat. No. 4,064,686, the yarn treating portion of the yarn part is also larger than the other portions, but the whole yarn path is solely cylindrical.